Refractory material



ANQ HELAIEB DEVIQES.

Patented June 12, 1928.

UNITED STATES it it PATENT orrlcs.

.rosnrn e. nonAnnson AND HENRY L. cones, or nAilmxron, 0x10, ssrenoas 'ro GUARDIAN mrrALs column. or HAMILTON, orno, A coarona'rrou or 1mm,

WARE.

REFRACTORY MATERIAL.

No Drawing. Original application flied November 17, 1922, Serial No. 811,616. Divided and this application filed January 16, 182t- Serial No. 2,864.

The subject matter of this invention was originally disclosed in the application for Letters Patent of Joseph G. Donaldson and Henry L, Coles, Serial No. 601,616, filed November 17, 1922, and entitled Metallic alloys and process of forming the same.

This invention relates to steel and other metals suitable for use in the safe and vault industry, particularly metals which will resist penetration by'the drill or b the local application of heat (asby the b ow torch) or both. In a previous application of Joseph G, Donaldson, Serial No. 478,220, filed June 17, 1921, entitled Metallic articles of manufacture and method of producing the same, we have described metals containing cores of highly refractory material,

which cores are encompassed in metal and preferably alloyed or united thereto. In our present invention we describe an improved material which may be utilized in the same way, i. e., as a core encompassed in metal. We do not, however, limit ourselves to the use of this material as a core as the same 7 has many commerical uses outside of its use as a core material.

We have found that highl refractory materials can beformed by ta ing a highmelting point. oxide-such as the oxide -of zirconium-and binding this together with a suitable binder such as a high-melting point silicate. Zirconium silicate has been found to'give excellent results for this pur ose. Preferably these materials should be nely comminuted and thoroughly mixed. They should then be placed in an electric furnace and heated for a sufiicient length of time to Illll) the whole mass to become thoroughly use Instead of adding the zirconium silicate as such, we have obtained excellent results by adding to the zirconium oxide approxl mately 9 to 11% silicon dioxide. When these substances have been comminuted and thoroughly mixed, the silicon dioxide and zirconium dioxide form zirconium silicate which, bein in contact with an excess of zirconium ioxide, forms mixed crystals with the same and acts as a binder for the entire mass. To either of the above substances we have found it highly advantageous to add from 7 to 10 per cent of carbon in a suitable form, such as graphite. A typical formula covering such a mixture is that these materials are detrimental to the formula and that the best results are obtained when either of these impurities constitutes less than 1% of the formula. The addition of carbon to the formula adds 70 very greatlv to the resistance of the finished material. -This is doubtless brought about by the fact that-the carbon forms metallic carbides which are present as crystals or in solid solution.

When the material herein described is used as a core, it is 'ven a suitable size and sha e and combin with a suitable metal, suc as steel, as by being encased wholly or partially therein. The core is preferably placed in a mould, metal (such as steel) being poured around-it, as described in our former application. Thereupon the core material and encompassing material are brought into permanent union by the alloying action w ich takes place at and adjacent to.the areas in contact. The mass so alloyed is more highl resistant to penetra tion either by the dri or by the torch than any other arts of the material not subject to such al oying action. In the matter of attempt to penetrate b means ofthe localized application of big heat, an important factor is the capacity of the material to con-1 duct the heat away from the point of at tack, thereby, in effect, diminishing the available cutting or fusing power of the torch. Refractory materials, of the type described, are excellent non-conductors of heat when cold but become conductors of heat when raised to a high temperatureand thus'serve to disipate the heat.

Cores containing a large zirconia have been found to s roportion of ink considerably when the same are cooled. To overcome this objection, we fre uently break u the core after the firstmeiting and rem e t same. The core formed by this second fusion will be found to be practically free from shrinkage cracks and to be more coherent than those cores which have been fused only once. These cores can be put in in strata which may be continuous throughout the metal or they may be placed in blocks which are set in staggered courses or the material may be broken into any desired size or the core may be formed by binding together with a suitable hinder the broken pieces, all as set forth in our previous application. In any event, the cores, made as herein described, are intensely hard and impenetrable by the drill. They are also substantially immune from attack by the blow torch.

Furthermore, the core material, being a non-conductor of electricity, it is im ossible to penetrate the same by means of t e local J any., 1925.

JOSEPH G. DONALDSON. HENRY L. COLES.

This specification signed this 8 day of 

